It is common to treat various types of fabrics during the laundering process with fabric-conditioning or treating agents to render the fabrics soft to the touch, to reduce tangling, knotting or wrinkling, to render them free of static electricity, to improve bacteria-resistance, to deodorize, and so forth, or to otherwise treat or condition them.
Since the advent of conditioning agents, consumers have come to expect fabrics emerging from the home laundering process to possess a certain level of softness, be relatively free of static, perfume, and so forth. An aqueous solution or dispersion of a fabric conditioning agent may be introduced during the washing or rinsing cycle of an automatic washing machine. Addition of the conditioner during the rinsing cycle is typically more effective in imparting the desired properties to the fabrics than addition during the washing cycle. The fabric conditioning agents are often of a cationic nature and are thus chemically incompatible with soaps and detergents which are typically anionic in nature. The addition of the conditioning agent during the final rinsing stage, however, requires manual addition of the conditioning agent by the consumer, a task which is often inconvenient, and as a consequence, is often forgotten. Furthermore, residual soaps and detergents are often present on the fabrics as a result of prior laundering which may also interfere with the use of these cationic conditioning agents even during the rinsing cycle.
Also, when applying an agent in a liquid dispersion or solution, there is typically about 16-20 times more solvent than agent which increases shipping and handling costs.
Attempts have therefore been made to deliver a benefit comparable to that obtained by the use of rinse conditioners, by adding fabric conditioner after the completion of the washing machine cycle, while the fabrics are drying in a tumble-dryer.
Flexible substrates coated or impregnated with a fabric softener and/or anti-static agent and designed for use in tumble dryers are commercially available and have become quite popular. Conditioning articles of the impregnated sheet type are described in U.S. Pat. No. 3,442,692.
There are, however, problems with the use of the impregnated sheet type of conditioners as well. For example, when conditioning articles of this type come into contact with a fabric in the tumble-dryer, conditioning agent is deposited locally, on the area of actual contact only. The deposition of conditioner may thus be non-uniform. If the fabric has an upstanding pile, such as with terrycloth towels or robes, for example, deposition may occur almost exclusively on the pile.
This problem is further compounded because these sheet type articles can become easily rolled, tangled and lodged in the fabrics being treated resulting in excessive dispensing of conditioning agent in one location, with a relatively small distribution of conditioning agent to the rest of the laundry load. The areas in contact with the fabric may thus become overloaded with conditioner while other areas of the load will not be conditioned at all. Overloading of conditioner in particular areas of fabric may lead to spotting and staining, although with current dryer sheets, such an occurrence is not as likely. The entanglement of the dryer sheet may also make the sheet difficult to locate and remove from the laundry.